U.S. patent number 10,316,115 [Application Number 15/100,510] was granted by the patent office on 2019-06-11 for process to visbreak propylene-based polymers with c--c initiators.
This patent grant is currently assigned to Dow Global Technologies LLC. The grantee listed for this patent is Dow Global Technologies LLC. Invention is credited to Mehmet Demirors, Sean W. Ewart, Teresa P. Karjala, Michael W. Tilston.
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United States Patent |
10,316,115 |
Karjala , et al. |
June 11, 2019 |
Process to visbreak propylene-based polymers with C--C
initiators
Abstract
The invention provides a process to prepare a second
propylene-based polymer from a first propylene-based polymer, each
propylene-based polymer having a melt flow rate (MFR; 2.16
kg/230.degree. C.) with the MFR of the second propylene-based
polymer greater than the MFR of the first propylene-based polymer,
the process comprising the step of contacting under visbreaking
conditions the first propylene-based polymer with at least one
carbon-carbon (C--C) free-radical initiator of Structure (I):
(Structure (I)) wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5
and R.sub.6 are each, independently, a hydrocarbyl group or a
substituted hydrocarbyl group, and wherein, optionally, two or more
R groups (R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6)
form a ring structure.
Inventors: |
Karjala; Teresa P. (Lake
Jackson, TX), Ewart; Sean W. (Pearland, TX), Demirors;
Mehmet (Pearland, TX), Tilston; Michael W. (Missouri
City, TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Assignee: |
Dow Global Technologies LLC
(Midland, MI)
|
Family
ID: |
52394340 |
Appl.
No.: |
15/100,510 |
Filed: |
December 17, 2014 |
PCT
Filed: |
December 17, 2014 |
PCT No.: |
PCT/US2014/070846 |
371(c)(1),(2),(4) Date: |
May 31, 2016 |
PCT
Pub. No.: |
WO2015/095320 |
PCT
Pub. Date: |
June 25, 2015 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20160297898 A1 |
Oct 13, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61918326 |
Dec 19, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L
23/10 (20130101); C08F 8/50 (20130101); C08F
110/06 (20130101); C08F 8/50 (20130101); C08F
110/06 (20130101); C08L 23/10 (20130101); C08L
23/10 (20130101); C08F 2810/10 (20130101) |
Current International
Class: |
C08F
8/50 (20060101); C08L 23/10 (20060101) |
Field of
Search: |
;524/582 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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9904066 |
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Apr 2001 |
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BR |
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0063654 |
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Nov 1982 |
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EP |
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0351208 |
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Jan 1990 |
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EP |
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1944327 |
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Jul 2008 |
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EP |
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06275129 |
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Sep 1994 |
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JP |
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2012/074812 |
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Jun 2012 |
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WO |
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2012/096962 |
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Jul 2012 |
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WO |
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Other References
EP. Otocka, et al., Macromolecules, vol. 4, No. 4, Jul.-Aug. 1971,
pp. 507-514. cited by applicant .
Th.G. Scholte, et al., J. Appl. Polym. Sci., vol. 29, 1984, pp.
3763-3782. cited by applicant.
|
Primary Examiner: Egwim; Kelechi C
Attorney, Agent or Firm: Husch Blackwell LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to U.S. patent application no.
61/918,326 filed on Dec. 19, 2013, the entire content of which is
incorporated by reference herein.
Claims
What is claimed is:
1. A process to prepare a second propylene-based polymer from a
first propylene-based polymer, each propylene-based polymer having
a melt flow rate (MFR; 2.16kg/230.degree. C.) with the MFR of the
second propylene-based polymer greater than the MFR of the first
propylene-based polymer, the process comprising the step of
contacting under visbreaking conditions in the absence of oxygen
and in the absence of oxygen-containing compounds the first
propylene-based polymer with at least one carbon-carbon (C-C)
free-radical initiator of Structure I: ##STR00012## wherein
R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are each,
independently, a C.sub.1-C.sub.12 hydrocarbyl group.
2. The process of claim 1, wherein R.sub.1, R.sub.2, R.sub.3,
R.sub.4, R.sub.5 and R.sub.6 are each, independently, a
C.sub.1-C.sub.8 hydrocarbyl group.
3. The process of claim 1 comprising contacting the first
propylene-based polymer with from 0.05 wt % to 0.5 wt % C-C
free-radical initiator, based on the weight of the first
propylene-based polymer.
4. The process of claim 1, wherein the C-C free-radical initiator
has a decomposition temperature of greater than 130.degree. C.
based on DSC measurements.
5. The process of claim 1, comprising contacting the first
propylene-based polymer with at least two different C-C
free-radical initiators.
6. The process of claim 1, wherein R.sub.1 and R.sub.4 are each a
phenyl group.
7. The process of claim 1, wherein the at least one C-C free
radical initiator is 3,4-diethyl-3,4-diphenyl hexane.
8. The process of claim 1, wherein the MFR of the second
propylene-based polymer is at least 130% of the MFR of the first
propylene based polymer.
9. The process of claim 1, wherein the visbreaking conditions
further include contacting the first propylene-based polymer with
the C-C free radical initiator under an inert atmosphere.
10. The process of claim 1, wherein the first propylene-based
polymer has a density from 0.83 g/cc to 0.90 g/cc.
11. The process of claim 10, wherein the first propylene-based
polymer has a molecular weight distribution from 3 to 5.
12. The process of claim 1, wherein the visbreaking conditions
further include activating the C-C free radical initiator by
radiation.
13. The process of claim 1 wherein the visbreaking conditions
further include contacting the first propylene-based polymer with
the C-C free radical initiator at a temperature from 200.degree. C.
to 350.degree. C.
14. The process of claim 1, wherein the at least one C-C free
radical initiator is selected from the group consisting of
2,3-dimethyl-2,3-diphenyl butane, 3,4-diethyl-3,4-diphenyl hexane,
3,4-diisobutyl-3,4-diphenyl hexane, 3,4-dibenzyl-3,4-ditolyl
hexane, 2,7-dimethyl-4,5-diethyl-4,5-diphenyl octane,
3,4-diethyl-3,4-di(dimethylphenyl) hexane,
3,4-dibenzyl-3,4-diphenyl hexane, poly-1,4-diisopropyl benzene, and
combinations thereof.
Description
BACKGROUND OF THE INVENTION
The conventional way of visbreaking polypropylene (PP) is by use of
organic peroxides. While organic peroxides increase the melt flow
rate (MFR) of the resin, the byproducts which are generated
(typically alcohols, ketones, aldehydes, etc.) impart strong taste
and odor to the resultant product. The carbon-carbon (C--C)
initiators do not have any oxygen in their structures and as such
do not generate those objectionable taste and odor components.
WO 2012/096962 discloses the use of "C-C containing" compounds as
antioxidants. WO 2012/074812 discloses the use of a "C-C
containing" compound as an impurity scavenger in the polymerization
of block copolymers. WO 2010/0108357 discloses the use of a "C--C
containing" compound as a crosslinking agent in a polymer
composition. U.S. Pat. No. 5,268,440 discloses the use of a C--C
initiator in an LDPE process. U.S. Pat. No. 6,967,229 discloses the
use of "C--C containing" compounds in the formation of golf ball
components. US 2006/0047049 discloses "C--C containing" compounds
in flame retardant compositions. There remains a need for new
processes to form visbroken propylene-based polymers with improved
properties. This need has been met by the following invention.
SUMMARY OF THE INVENTION
The invention provides a process to prepare a second
propylene-based polymer from a first propylene-based polymer, each
propylene-based polymer having a melt flow rate (MFR; 2.16
kg/230.degree. C.) with the MFR of the second propylene-based
polymer greater than the MFR of the first propylene-based polymer,
the process comprising the step of contacting under visbreaking
conditions the first propylene-based polymer with at least one
carbon-carbon (C--C) free-radical initiator of Structure I:
##STR00001## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5
and R.sub.6 are each, independently, a hydrocarbyl group or a
substituted hydrocarbyl group, and wherein, optionally, two or more
R groups (R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6)
form a ring structure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a DSC profile of DEDPH, showing melting peak at
45.1.degree. C. and decomposition peak at 202.7.degree. C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention provides a process to prepare a second
propylene-based polymer from a first propylene-based polymer, each
propylene-based polymer having a melt flow rate (MFR; 2.16
kg/230.degree. C.) with the MFR of the second propylene-based
polymer greater than the MFR of the first propylene-based polymer,
the process comprising the step of contacting under visbreaking
conditions the first propylene-based polymer with at least one
carbon-carbon (C--C) free-radical initiator of Structure I:
##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5
and R.sub.6 are each, independently, a hydrocarbyl group or a
substituted hydrocarbyl group, and wherein, optionally, two or more
R groups (R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6)
form a ring structure.
An inventive process may comprise a combination of two or more
embodiments as described herein.
In one embodiment, the C-C free-radical initiator is present in an
amount greater than, or equal to, 0.12 grams per kilogram (g/kg),
further greater than 0.20 grams per kilogram, further greater than
0.50 grams per kilogram, further greater than 0.70 grams per
kilogram, of the first propylene-based polymer.
In one embodiment, the C-C free-radical initiator is present in an
amount greater than, or equal to, 1.00 grams per kilogram (g/kg),
further greater than 1.20 grams per kilogram, further greater than
1.50 grams per kilogram, of the first propylene-based polymer.
In one embodiment, the C-C free-radical initiator has a
decomposition temperature of greater than (>) or equal to
125.degree. C., or >130.degree. C., or >150.degree. C., or
>180.degree. C., or >200.degree. C., or >250.degree. C.,
or >300.degree. C., based on DSC measurements.
In one embodiment, the process comprises decomposing or activating
the C--C free radical initiator by radiation.
In one embodiment, the process comprises contacting the first
propylene-based polymer with at least two C--C free-radical
initiators.
In one embodiment, for Structure I, R.sub.1 and R.sub.4 are
phenyl.
In one embodiment, for Structure I, the at least one C--C initiator
is selected from the group consisting of 2,3-dimethyl-2,3-diphenyl
butane; 3,4-dimethyl-3,4-diphenyl hexane; and
3,4-diethyl-3,4-diphenyl hexane.
In one embodiment, the MFR of the second propylene-based polymer is
less than or equal to (.ltoreq.), 200 g/10 min, further .ltoreq.150
g/10 min, further .ltoreq.100 g/10 min, further .ltoreq.90 g/10
min.
In one embodiment, the MFR of the second propylene-based polymer is
greater than or equal to (.gtoreq.) 10 g/10 min, further .gtoreq.20
g/10 min, further .gtoreq.50 g/10 min, but .ltoreq.90 g/10 min.
In one embodiment, the MFR of the second propylene-based polymer is
.gtoreq.100 g/10 min, further .gtoreq.200 g/10 min, further
.gtoreq.500 g/10 min, further .gtoreq.1000 g/10 min.
In one embodiment, the MFR of the second propylene-based polymer is
at least 130%, or at least 150%, or at least 200%, or at least
300%, or at least 400% of the MFR of the first propylene based
polymer.
In one embodiment, the first propylene-based polymer is contacted
with at least one carbon-carbon (C--C) free-radical initiator of
Structure I, and at least one peroxide.
In one embodiment, the molar ratio of the carbon-carbon free
radical initiator to the peroxide is greater than 1.0, further
greater than 1.5, further greater than 2.0.
An inventive process may comprise a combination of two or more
embodiments as described herein.
The invention also provides a composition comprising the second
propylene-based polymer formed by the process of any one of the
previous claims.
In one embodiment, the second propylene-based polymer has a tert
butanol level .ltoreq.1.0 ppm, or .ltoreq.0.9 ppm, or .ltoreq.0.8
ppm.
In one embodiment, the second propylene-based polymer has a density
.ltoreq.0.90 g/cc, further .ltoreq.0.89 g/cc, and further
.ltoreq.0.88 g/cc.
In one embodiment, the second propylene-based polymer has a density
.ltoreq.0.83 g/cc, further .ltoreq.0.84 g/cc, and further
.ltoreq.0.85 g/cc.
In one embodiment, the second propylene-based polymer has a density
from 0.83 g/cc, to 0.90 g/cc, further from 0.84 g/cc to 0.89 g/cc,
and further from 0.85 g/cc to 0.88 g/cc.
In one embodiment, the second propylene-based polymer has a density
.ltoreq.0.946 g/cc, further .ltoreq.0.93 g/cc, and further
.ltoreq.0.91 g/cc.
In one embodiment, the second propylene-based polymer has a density
from 0.83 g/cc to 0.946 g/cc, further from 0.88 g/cc to 0.93 g/cc,
and further from 0.89 g/cc to 0.91 g/cc.
In one embodiment, the second propylene-based polymer has a
molecular weight distribution from 1.5 to 6, further from 2.5 to
5.5, and further from 3 to 5.
In one embodiment, the composition further comprises one or more
additives.
An inventive composition may comprise a combination of two or more
embodiments as described herein.
The invention also provides an article comprising at least one
component formed from an inventive composition as described herein.
In a further embodiment, the article is a film or a coating.
An inventive article may comprise a combination of two or more
embodiments as described herein.
The second propylene-based polymer may comprise a combination of
two or more embodiments as described herein.
The first propylene-based polymer may comprise a combination of two
or more embodiments as described herein.
C--C Initiators
The carbon-carbon ("C--C") initiators used in the practice of this
invention have Structure I:
##STR00003##
wherein R.sub.1-R.sub.6 are each, independently, a hydrocarbyl or a
substituted hydrocarbyl group, and wherein optionally two or more
R.sub.1-R.sub.6 groups may form a ring structure.
In one embodiment, one or more of the R.sub.1-R.sub.6 groups are
aliphatic.
In one embodiment, one or more of the R.sub.1-R.sub.6 groups are
alkyl.
In one embodiment, one or more of the R.sub.1-R.sub.6 groups are
aryl.
In one embodiment, the R.sub.1-R.sub.6 are each, independently, an
hydrocarbyl group, and wherein optionally two or more
R.sub.1-R.sub.6 groups may form a ring structure.
In one embodiment, the R.sub.1 -R.sub.6 are each, independently, a
hydrocarbyl or a substituted hydrocarbyl group.
In one embodiment, the R.sub.1-R.sub.6 are each, independently, a
substituted hydrocarbyl group, and wherein optionally two or more
R.sub.1-R.sub.6 groups may form a ring structure.
In one embodiment, the R.sub.1-R.sub.6 are each, independently, a
C.sub.1-24 hydrocarbyl or a C.sub.1-24 substituted hydrocarbyl
group, and wherein optionally two or more R.sub.1 -R.sub.6 groups
may form a ring structure.
In one embodiment, the R.sub.1-R.sub.6 are each, independently, a
C.sub.1-24 hydrocarbyl group, and wherein optionally two or more
R.sub.1-R.sub.6 groups may form a ring structure.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C .sub.1-24 hydrocarbyl or a C.sub.1-24
substituted hydrocarbyl group.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C.sub.1-24 substituted hydrocarbyl group, and
wherein optionally two or more R.sub.1-R.sub.6 may form a ring
structure.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently a C.sub.1-12 hydrocarbyl or a C.sub.1-12 substituted
hydrocarbyl group, and wherein optionally two or more
R.sub.1-R.sub.6 groups may form a ring structure.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C.sub.1-12 hydrocarbyl group, and wherein
optionally two or more R.sub.1-R.sub.6 groups may form a ring
structure.
In one embodiment, the R.sub.1-R.sub.6 are each, independently, a
C.sub.1-12 hydrocarbyl or C.sub.1-12 substituted hydrocarbyl
group.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C.sub.1-12 substituted hydrocarbyl group, and
wherein optionally two or more R.sub.1 -R.sub.6 groups may form a
ring structure.
In one embodiment, the R.sub.1-R.sub.6 are each, independently a
C.sub.1-6 hydrocarbyl or a C.sub.1-6 substituted hydrocarbyl group,
and wherein optionally two or more R.sub.1-R.sub.6 groups may form
a ring structure.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C.sub.1-6 hydrocarbyl group, and wherein
optionally two or more R.sub.1-R.sub.6 groups may form a ring
structure.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C .sub.1-6 hydrocarbyl or C.sub.1-6 substituted
hydrocarbyl group.
In one embodiment, the R.sub.1-R.sub.6 groups are each,
independently, a C.sub.1-6 substituted hydrocarbyl group, and
wherein optionally two or more R.sub.1-R.sub.6 may form a ring
structure.
In one embodiment R.sub.1 and R.sub.4 are the same or different
aryl radicals. In a further embodiment, R.sub.1 and R.sub.4 are
each phenyl, e.g., Structure II; and wherein R.sub.2, R.sub.3,
R.sub.5 and R.sub.6 are each as described above:
##STR00004##
In one embodiment, R.sub.2-R.sub.3 and R.sub.5-R.sub.6 are the same
or different alkyl radicals, more preferably the same or different
C.sub.1-6 alkyl radicals, and even more preferably the same
C.sub.14 straight chain alkyl radical.
Representative C-C initiators include, but are not limited to, the
following Structures as follows: 2,3 -dimethyl-2,3 -diphenyl butane
(Structure III)
##STR00005## 3 ,4-dimethyl-3 ,4-diphenyl hexane (Structure IV)
##STR00006## and, 3,4-diethyl-3,4-diphenyl hexane (Structure V)
##STR00007## 2,7-dimethyl-4,5-diethyl-4,5-diphenyl octane (DBuDPH)
(Structure VI)
##STR00008## 3,4-dibenzyl-3,4-ditolyl hexane (DBnDTH) (Structure
VII)
##STR00009## 3,4-diethyl-3,4-di(dimethylphenyl) hexane (Structure
VIII)
##STR00010## and, 3,4-dibenzyl-3,4-diphenyl hexane (Structure
IX)
##STR00011##
Other C--C initiators include poly-1,4-diisopropyl benzene,
1,1,2,2-tetraphenyl-1,2-ethane diol, and those of Structure 1 and
described in such publications as WO 2012/096962, WO 2012/074812,
US 2010/0108357, EP 1 944 327, U.S. Pat. No. 5,268,440, U.S. Pat.
No. 6,967,229 and US 2006/0047049. The C--C initiators can be used
alone or in combination with one another.
In one embodiment, the amount of C--C initiator used in the
practice of this invention is typically at least 0.05 wt %, more
typically at least 0.10 wt %, and even more typically at least 0.20
wt % based on the weight of the first propylene-based polymer.
While the only limitation on the maximum amount of C--C initiator
used in the practice of this invention is a function of process
economics and efficiency, typically the maximum amount of C-C
initiator used in the practice of this invention does not exceed 1
wt %, more typically does not exceed 0.8 wt % and even more
typically does not exceed 0.5 wt %, based on the weight of the
first propylene-based polymer.
A C--C initiator may comprise a combination of two or more
embodiments as described herein.
First Propylene-Based Polymer
The propylene-based polymers used as the "first propylene-based
polymer" include both propylene homopolymers and propylene
interpolymers and copolymers.
In one embodiment, the first propylene-based polymer is a propylene
copolymer. In a further embodiment, the first propylene copolymer
comprises more than 50 wt % units derived from propylene, typically
more than 60 wt % and more typically more than 70 wt %, units
derived from propylene with the remainder of the polymer comprising
units of one or more comonomers, typically an alpha-olefin monomer
such as ethylene, butene, pentene, hexene, octene and the like.
First propylene copolymers can also include units derived from
diener such as butadiene, isoprene, cyclopentadiene and the
like.
In one embodiment the propylene-based polymers before visbreaking,
i.e., the first propylene-based polymer, contain little (e.g., less
than (<) 1 wt %, or <0.5 wt %, or <0.1 wt %), if any,
peroxide or oxygen.
The propylene-based polymers before visbreaking, i.e., the first
propylene-based polymer, typically have a melt flow rate (MFR) of
less than or equal to (.ltoreq.) 50 grams per 10 minute (g/10 min),
more typically .ltoreq.25, or .ltoreq.20, or .ltoreq.10, or
.ltoreq.5, or .ltoreq.1, or .ltoreq.0.5, or .ltoreq.0.1, g/10
min.
The propylene-based polymers after visbreaking, i.e., the second
propylene-based polymer, typically have a MFR more than 130%,
typically more than (>) 150%, or >200%, or >300%, of their
MFR before visbreaking. In one embodiment the second
propylene-based polymer typically has an MFR greater than or equal
to (.gtoreq.) 0.13, or .gtoreq.0.15, or .gtoreq.0.2, or
.gtoreq.0.3, or .gtoreq.0.5, or .gtoreq.1, or .gtoreq.5,
.gtoreq.10, or .gtoreq.20, or .gtoreq.30, or .gtoreq.40, or
.gtoreq.50, or .gtoreq.60, or .gtoreq.70, or .gtoreq.80, or
.gtoreq.90, or .gtoreq.100, or .gtoreq.200, or .gtoreq.300, g/10
min. In one embodiment the second propylene-based polymer has a MFR
from 0.13 to 300, or from 0.13 to 200, or from 0.13 to 100, or from
0.13 to 50, or from 0.13 to 20, or from 0.13 to 10, g/10 min.
Suitable first propylene-based polymers include propylene
homopolymers and propylene interpolymers. The polypropylene
homopolymer can be isotactic, syndiotactic or atactic
polypropylene. The propylene interpolymer can be a random or block
copolymer, or a propylene-based terpolymer. Reactor copolymers of
polypropylene may also be used.
Suitable comonomers for polymerizing with propylene include
ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,
1-nonene, 1-decene, 1-undecene, 1-dodecene, as well as
4-methyl-l-pentene, 4-methyl-l-hexene, 5-methyl-l-hexene,
vinylcyclohexane, and styrene. The preferred comonomers include
ethylene, 1-butene, 1-hexene, and 1-octene, and more preferably
ethylene.
Suitable first propylene-based polymers include Dow 5D98 and other
polypropylene homopolymers and copolymers (now available from
Braskem); VERSIFY plastomers and elastomers (The Dow Chemical
Company) and VISTAMAXX polymers (ExxonMobil Chemical Co.), LICOCENE
polymers (Clariant), EASTOFLEX polymers (Eastman Chemical Co.),
REXTAC polymers (Hunstman), VESTOPLAST polymers (Degussa), PROFAX
PF-611 and PROFAX PF-814 (Montell).
In one embodiment, the first propylene-based polymer has a density
less than, or equal to (.ltoreq.), 0.90 g/cc, preferably
.ltoreq.0.89 g/cc, and more preferably .ltoreq.0.88 g/cc.
In one embodiment, the first propylene-based polymer has a density
greater than or equal to (.gtoreq.) 0.83 g/cc, preferably
.gtoreq.0.84 g/cc, and more preferably .gtoreq.0.85 g/cc.
In one embodiment, the first propylene-based polymer has a density
from 0.83 g/cc to 0.90 g/cc, and preferably from 0.84 g/cc to 0.89
g/cc, and more preferably from 0.85 g/cc to 0.88 g/cc.
In one embodiment, the first propylene-based polymer has a
molecular weight distribution from 1.5 to 6, and more preferably
from 2.5 to 5.5, and more preferably from 3 to 5.
The first propylene-based polymer may have a combination of two or
more suitable embodiments as described herein.
Visbreaking Process
The visbreaking process of this invention comprises the step of
contacting a first propylene-based polymer with a C-C free radical
initiator under visbreaking conditions, preferably in the absence
of oxygen and typically under an inert atmosphere, e.g., nitrogen.
Visbreaking conditions typically include a temperature at which the
first propylene-based polymer is molten and the C-C free radical
initiator will decompose to form free radicals, e.g., from
200.degree. C. to 350.degree. C., or from 200.degree. C. to
300.degree. C., or from 210.degree. C. to 270.degree. C. In one
embodiment the visbreaking conditions include decomposing or
activating the C-C free radical initiator by exposing the same to
radiation.
The contacting is typically performed in conventional mixing
apparatus, e.g., mixing extruder, batch mixer, etc., and continues
until the MFR of the first propylene-based polymer is increased to
the desired level. The C--C initiator can be added to the polymer
at one time, or metered into the polymer over time. Additives,
e.g., stabilizers, can be present in the polymer during the mixing
operation.
Additives
An inventive composition may comprise one or more additives.
Additives include, but are not limited to, stabilizers, antistatic
agents, pigments, dyes, nucleating agents, fillers, slip agents,
fire retardants, plasticizers, processing aids, lubricants,
stabilizers, smoke inhibitors, viscosity control agents,
anti-blocking agents, and combinations thereof. Typically, the
inventive compositions contain one or more stabilizers, for
example, antioxidants, such as IRGANOX 1010 and IRGAFOS 168, both
supplied by Ciba Specialty Chemicals. Polymers are typically
treated with one or more stabilizers before an extrusion or other
melt processes.
DEFINITIONS
Unless stated to the contrary, implicit from the context, or
customary in the art, all parts and percents are based on weight,
and all test methods are current as of the filing date of this
disclosure. For purposes of United States patent practice, the
contents of any referenced patent, patent application or
publication are incorporated by reference in their entirety (or its
equivalent US version is so incorporated by reference) especially
with respect to the disclosure of definitions (to the extent not
inconsistent with any definitions specifically provided in this
disclosure) and general knowledge in the art.
"Comprising", "including", "having" and like terms mean that the
composition, process, etc. is not limited to the components, steps,
etc. disclosed, but rather can include other, undisclosed
components, steps, etc. In contrast, the term "consisting
essentially of" excludes from the scope of any composition,
process, etc. any other component, step etc., excepting those that
are not essential to the performance, operability or the like of
the composition, process, etc. The term "consisting of" excludes
from a composition, process, etc., any component, step, etc., not
specifically disclosed. The term "or", unless stated otherwise,
refers to the disclosed members individually as well as in any
combination.
The term "polymer," as used herein, refers to a polymeric compound
prepared by polymerizing monomers, whether of the same or a
different type. The generic term polymer thus embraces the term
homopolymer (employed to refer to polymers prepared from only one
type of monomer), and the term interpolymer as defined hereinafter.
Trace amounts of impurities, such as catalyst residues, may be
incorporated into or within a polymer.
The term "interpolymer," as used herein, refers to polymers
prepared by the polymerization of at least two different types of
monomers. The generic term interpolymer thus includes copolymers
(employed to refer to polymers prepared from two different types of
monomers), and polymers prepared from more than two different types
of monomers.
The term "propylene-based polymer," as used herein, refers to a
polymer that comprises at least a majority weight percent
polymerized propylene (based on the weight of polymer), and,
optionally, one or more additional comonomers.
"Hydrocarbyl," and like terms, refer to a radical consisting of
carbon and hydrogen atoms. Nonlimiting examples of hydrocarbyl
radicals include alkyl (straight chain, branched or cyclic), aryl
(e.g., phenyl, naphthyl, anthracenyl, biphenyl), aralkyl (e.g.,
benzyl), and the like.
"Substituted hydrocarbyl," and like terms, refer to a hydrocarbyl
radical, in which one or more hydrogen atoms bound to any carbon of
the hydrocarbyl radical, and/or one or more carbon atoms of the
hydrocarbyl radical, is/are, independently, replaced by one of the
following: i) a heteroatom, or ii) a group, comprising at least one
heteroatom, and other than a peroxy group (--OOH). Nonlimiting
examples of heteroatoms include halogen, nitrogen, sulfur, oxygen.
Nonlimiting examples of groups, other than a peroxy group, include
haloalkyl, hydroxy, amino, phosphido, alkoxy, amino, thio, nitro,
and combinations thereof.
"Aliphatic hydrocarbon" and like terms mean a branched or
unbranched or cyclic, saturated or unsaturated, hydrocarbon
radical. Nonlimiting examples of suitable aliphatic radicals
include methyl, ethyl, n-propyl, i-propyl, 2-propenyl (or allyl),
vinyl, n-butyl, t-butyl, i-butyl (or 2-methylpropyl), cyclopentyl,
cyclohexyl, and the like. In one embodiment, the aliphatic radicals
are alkyl radicals of 1 to 24 carbon atoms.
"Aryl" and like terms mean an aromatic radical which may be a
single aromatic ring or multiple aromatic rings which are fused
together, linked covalently, or linked to a common group such as a
methylene or ethylene moiety. Nonlimiting examples of aromatic
ring(s) include phenyl, naphthyl, anthracenyl, biphenyl, among
others. In one embodiment, the aryl radicals typically comprise 6
to 20 carbon atoms.
Test Method
Melt Flow Rate: Also known as MFR (grams/10 minutes or dg/min) is
measured in accordance with ASTM D 1238, Condition 230.degree.
C./2.16 kg.
High Temperature Gel Permeation Chromatography (GPC): The polymers
are analyzed on a PL-220 series high temperature gel permeation
chromatography (GPC) unit, equipped with a refractometer detector
and four PLgel Mixed-A (20 .mu.m) columns (Polymer Laboratory
Inc.). The oven temperature is set at 150.degree. C., and the
temperatures of the autosampler's hot and the warm zones are set at
135.degree. C. and 130.degree. C., respectively. The solvent is
nitrogen purged 1,2,4-trichlorobenzene (TCB), containing about 200
parts per million (ppm) 2,6-di-t-butyl-4-methylphenol (BHT). The
flow rate is 1.0 mL/min, and the injection volume is 200
microliters (.mu.l). A 2 milligram per liter (mg/mL) sample
concentration is prepared by dissolving the sample in N.sub.2
purged and preheated TCB (containing 200 ppm BHT), for 2.5 hours at
160.degree. C., with gentle agitation.
The GPC column set is calibrated by running twenty narrow molecular
weight distribution polystyrene standards. The molecular weight
(Mw) of the standards ranges from 580 to 8,400,000 g/mol, and the
standards are contained in six "cocktail" mixtures. Each standard
mixture has at least a decade of separation between individual
molecular weights. The polystyrene standards are prepared at "0.005
g in 20 mL" of solvent for molecular weights equal to, or greater
than, 1,000,000 g/mol, and at "0.001 g in 20 mL" of solvent for
molecular weights less than 1,000,000 g/mol. The polystyrene
standards are dissolved at 150.degree. C. for 30 minutes, under
stirring. The narrow molecular weight distribution standards
mixtures are run first, and in order of decreasing highest
molecular weight component, to minimize the degradation effect. A
logarithmic molecular weight calibration is generated, using a
fourth-order polynomial fit as a function of elution volume. The
equivalent polypropylene molecular weights are calculated by using
the following equation, with reported Mark-Houwink coefficients for
polypropylene (Th. G. Scholte, Meijerink, H. M. Schoffeleers, and
A. M. G. Brands, J. Appl. Polym. Sci., 29, 3763-3782 (1984)) and
polystyrene (E. P. Otocka, R. J. Roe, N. Y. Hellman, P. M. Muglia,
Macromolecules, 4, 507 (1971)):
.times. ##EQU00001##
where M.sub.pp is the polypropylene (PP) equivalent molecular
weight (MW), M.sub.PS is the polystyrene (PS) equivalent MW, log K
and a are values of the Mark-Houwink coefficients for PP and PS and
are listed below:
TABLE-US-00001 Polymer a log K Polypropylene 0.725 -3.721
Polystyrene 0.702 -3.900
The calculations of Mn, Mw and Mz based on GPC results, using the
refractometer detector (dRI) and the narrow molecular weight
distribution standards calibration, are determined from the
following equations:
.times..times..times..times. ##EQU00002##
.times..times..times..times. ##EQU00002.2##
.times..times..times..times..times..times. ##EQU00002.3## In the
above equations, dRI.sub.i and M.sub.PP,i are the dRI baseline
corrected response and conventional calibrated polypropylene
molecular weight, respectively, for the i.sup.th slice of the dRI
response.
Test Method for Tert-Butyl Alcohol Determination: The tert-butyl
alcohol level in polypropylene is determine using headspace gas
chromatography on an Agilent model 6890 gas chromatograph equipped
with headspace sampler model 7694 with a flame ionization detector
available from Agilent Technologies, Wilmington, Del. About one
gram of polypropylene pellets (weighed and recorded to the nearest
0.0001 g) is placed into a headspace vial and sealed. The sample is
equilibrated at 150.degree. C. for one hour in the headspace vial.
The headspace is analyzed and the peak area determined for
tert-butyl alcohol. Quantitation is performed using an external
standard calibration method with the previously determined
distribution constant for tert-butyl alcohol in polypropylene at
150.degree. C.
Differential Scanning Calorimetry (DSC): DSC is performed under a
nitrogen headspace, from an initial temperature of 0.degree. C. up
to a final temperature of 400.degree. C., at a scan rate of
10.degree. C. per minute. The sample amount was about 10 mg.
Density: Samples for density measurements are prepared according to
ASTM D 4703-10. Samples are pressed at 374.degree. F. (190.degree.
C.), for five minutes, at 10,000 psi (68 MPa). The temperature is
maintained at 374.degree. F. (190.degree. C.) for the above five
minutes, and then the pressure is increased to 30,000 psi (207 MPa)
for three minutes. This is followed by a one minute hold at
70.degree. F. (21.degree. C.) and 30,000 psi (207 MPa).
Measurements are made within one hour of sample pressing using ASTM
D792-08, Method B.
EXAMPLES
Experiments were run using a HAAKE mixer. DOW 5D98 is a
polypropylene (first propylene-based polymer) having a melt flow
rate (MFR) of 3.4 g/10 min and density of 0.900 g/cc (now available
from Braskem). Table 1 provides the properties of various C--C
initiators used in the examples.
TABLE-US-00002 TABLE 1 Properties of C-C Initiators 3 times
Equivalent equivalent radical (ppm) radical (ppm) Breaks DSC to
1000 ppm to 1000 pm into Mw decomposition TRIGONOX TRIGONOX
Initiator Name X radicals (g/mol) peak.sup.a (C.) 101.sup.b
101.sup.b 3,4-diethyl-3,4- DEDPH 2 294.5 202.7 2,028 6,085 diphenyl
hexane 2,3-dimethyl-2,3- DMDPB 2 238.4 309.3 1,642 NM dipihenyl
butane 3,4-dimethyl-3,4- DMDPH 2 266.4 277.5 1,835 5,504 diphenyl
hexane TRIGONOX 101 Trig 101 4 290.4 183.5 1,000 NM
3,4-diisobutyl-3,4- DBuDPH 2 350.6 135 2,415 NM diphenyl hexane
3,4-dibenzyl-3,4- DBnDTH 2 448.6 130 3,090 NM ditolyl hexane
.sup.aDSC decomposition peak is the temperature at which
decomposition occurs on the DSC scan, the scan may also show
melting or crystallization peaks (see FIG. 1 for a typical DSC
curve of DEDPH; decomposition temperature measured at the peak of
the decomposition exotherm). .sup.bEquivalent radicals is defined
as the weight ppm required of each initiator to produce the same
number of moles of radicals as 1000 weight ppm of TRIGONOX 101. NM
= not measured.
Preparation of Samples in RS5000 Torque Rheometer with HAAKE 600
Mixing Bowl:
Polymer samples were melt blended with various levels of specified
additives in a heated RS5000 drive and HAAKE RHEOMIX 600 mixer. A
61% filling level of the mixing chamber was used, i.e., 61% of the
volume of the chamber was filled with sample. The sample weight
used was approximated as: The sample weight =bulk density of the
material (0.900 g/cm.sup.3).times.net chamber volume (69
cm.sup.3).times.the filling fraction (0.61).about.37.9 g.
The mixer was equipped with 25% GF (glass filled) TEFLON custom
made bushings and roller style rotors. All of the materials (the
polypropylene and the C-C initiators or peroxides) were added to
the chamber, and then nitrogen purging was started during the
melting and mixing of the materials. After the materials were added
to the chamber, the nitrogen purge was started within 1-2 minutes.
The nitrogen purge was at a low enough rate to not cause a
significant temperature decrease of the melt or a "skin" on the
melt surface of the sample in the nip between the rotors.
Molded capsules from the PP 5D98 were used for addition of
additives into the heated mixer. The molded capsules were made with
a custom made mold to mold the top and bottom of the capsule at
190.degree. C. with no pressure in a manual PHI bench top press for
about 5 minutes. The mold with the capsules was cooled to room
temperature in air until cool enough to handle. The capsules were
about 1-1.5 g in weight. This capsule weight was included in the
weight of the sample's base polymer added to the mixer. The
additive was then weighed into the capsule. This additive capsule
was added into the mixer with the polymer pellets, using the ram to
keep material in the mixer, until melted, about 40 seconds to one
minute. Then the nitrogen block was put into the mixer opening to
reduce atmospheric oxygen during the melt processing. See Table 2
for the polymer formulations.
The temperature was controlled in the bowl (Zone 2) using a melt
thermocouple which touches the polymer (flush with the bowl
surface). This thermocouple measures the polymer melt as it is
processed. Zones 1 and 3 thermocouples were used to control the set
temperature of these zones (the thermocouples in these cases are in
the block but do not touch the polymer). The temperature of the
polymer melt as set and measured by Zone 2 is shown in Table 2
(temperatures were either 210.degree. C., 240.degree. C., or
270.degree. C.). The revolutions per minute (rpm) were 50, and the
mixing time was 10 minutes for all samples.
Samples (about 38 g minus about 2 g which were unable to be easily
removed from the chamber) were quickly removed from the hot mixer
by scraping out with a stainless steel spatula onto TEFLON coated
sheets, and immediately quench cooled, by pressing in a Carver hot
press (the set point of the cooling fluid in the platens was
18.degree. C., 3-5 minutes, 20,000 psi) the hot sample between the
chilled platens of a CARVER hydraulic press to form a "pancake" of
about 3/8-1/2 inches in thickness.
The visbreaking conditions are also summarized in Table 2,
below.
Table 3 provides the melt flow rates of the examples described in
Table 2, and Table 4 provides further molecular weight properties
of the examples after visbreaking. Samples comprising TRIGONOX 101
are comparative samples.
TABLE-US-00003 TABLE 2 Polymer Formulations and Visbreaking
Conditions Polymer Level of Melt Run Initiator Temp. # Name
Initiator (ppm)* (.degree. C.) 1 PP 5D98 None 0 210 2 PP 5D98 +
1,000 ppm Trig 101 Trig. 101 1,000 210 3 PP 5D98 + 2.028 ppm DEDPH
DEDPH 2,028 210 4 PP 5D98 + 1,642 ppm DMDPB DMDPB 1,642 210 5 PP
5D98 + 1,835 ppm DMDPH DMDPH 1,835 210 6 PP 5D98 + 2,415 ppm DBuDPH
DBuDPH 2,415 210 7 PP 5D98 + 3,090 ppm DBuDPH DBnDTH 3,090 210 8 PP
5D98 None 0 240 9 PP 5D98 + 1,000 ppm Trig 101 Trig. 101 1,000 240
10 PP 5D98 + 2,028 ppm DEDPH DEDPH 2,028 240 11 PP 5D98 + 1,642 ppm
DMDPB DMDPB 1,642 240 12 PP 5D98 + 1,835 ppm DMDPH DMDPH 1,835 240
13 PP 5D98 + 2,415 ppm DBuDPH DBuDPH 2,415 240 14 PP 5D98 + 3,090
ppm DBuDPH DBnDTH 3,090 240 15 PP 5D98 None 0 270 16 PP 5D98 +
1,000 ppm Trig 101 Trig. 101 1,000 270 17 PP 5D98 + 1,642 ppm DMDPB
DMDPB 1,642 270 *The ppm amount based on weight of first
propylene-based polymer.
TABLE-US-00004 TABLE 3 Melt Flow Rate at 230.degree. C.; 2.16 kg,
after visbreaking (units: g/10 min) Melt PP 5D98 + PP 5D98 + PP
5D98 + PP 5D98 + PP 5D98 + PP 5D98 + PP 5D98 + Temp. 1,000 ppm
2,028 ppm 6,085 ppm 1,642 ppm 1,835 ppm 2,415 ppm 3,090 ppm
(.degree. C.) PP 5D98 Trig 101 DEDPH DEDPH DMDPB DMDPH DBuDPH
DBnDTH 210 4.4 65.3 13.4 19.3 7.4 9.6 9.7 10.4 240 9.0 138.9 26.7
28.2 15.0 23.3 18.1 12.1 270 32.5 118.9 Sample not 73.8 58.8 85.8
Sample not Sample not made made made
TABLE-US-00005 TABLE 4 GPC Moments after Visbreaking Mn Mw Mz
Sample (g/mol) (g/mol) (g/mol) Mw/Mn PP 5D98 63,495 360,175
1,273,486 5.67 PP 5D98 (210 C.) 62,169 347,267 1,155,680 5.59 PP
5D98 (240 C.) 61,567 302,002 892,828 4.91 PP 5D98 (270 C.) 27,933
131,627 324,007 4.71 PP 5D98 + 1,000 ppm Trig 101 (210 C.) 43,643
140,810 295,319 3.23 PP 5D98 + 1,000 ppm Trig 101 (240 C) 40,829
128,480 259,375 3.15 PP 5D98 + 1,000 ppm Trig 101 (270 C.) 24,196
84,745 186,242 3.50 PP 5D98 + 3,090 ppm DBuDPH (210 C.) 57,514
259,282 673,274 4.51 PP 5D98 + 3,090 ppm DBuDPH (240 C.) 35,790
159,046 403,303 4.44 PP 5D98 + 1,642 ppm DMDPB (210 C.) 59,264
309,407 915,222 5.22 PP 5D98 + 1,642 ppm DMDPB (240 C.) 37,317
159,063 404,183 4.26 PP 5D98 + 1,642 ppm DMDPB (270 C.) 19,629
100,674 230,088 5.13 PP 5D98 + 2,415 ppm DBuDPH (210 C.) 57,105
262,076 682,372 4.59 PP 5D98 + 2,415 ppm DBuDPH (240 C.) 31,383
132,084 315,032 4.21 PP 5D98 + 2,028 ppm DEDPH (210 C.) 56,282
247,960 628,099 4.41 PP 5D98 + 2,028 ppm DEDPH (240 C.) 49,811
202,198 466,238 4.06 PP 5D98 + 6,085 ppm DEDPH (210 C.) 53,033
220,690 539,271 4.16 PP 5D98 + 6,085 ppm DEDPH (240 C.) 48,783
193,574 445,976 3.97 PP 5D98 + 6,085 ppm DEDPH (270 C.) 36,753
148,761 328,950 4.05 PP 5D98 + 1,835 ppm DMDPH (210 C.) 59,530
271,958 723,204 4.57 PP 5D98 + 1,835 ppm DMDPH (240 C.) 33,330
133,681 322,289 4.01 PP 5D98 + 1 835 ppm DMDPH (270 C.) 40,757
152,192 339,047 3.73
As shown in Table 3, the melt flow rate of the second
propylene-based polymer increases after visbreaking, with DEDPH and
DMDPH (C--C initiators), showing the most significant increase,
with final melt flow rates (at 270.degree. C.) very similar to
those obtained with TRIGONOX 101. Table 3 also shows that some C-C
initiators (such as DEDPH and DMDPB) are more effective at higher
temperatures, while others (such as DBnDTH) are more effective at
lower temperatures. As shown in Table 4, the Mw/Mn values of the
inventive examples using C-C initiators are generally greater than
that of the comparative examples using TRIGONOX 101.
Table 5 demonstrates the level of tert-butanol, a known
odor-causing compound measured in these polymer samples. The
polymer from the comparative example made with TRIGONOX 101 shows a
t-butanol level greater than 1 ppm, whereas the polymer samples
made with the new initiators, in most cases, show non-detectable or
very low levels.
TABLE-US-00006 TABLE 5 Tert-Butanol values after Visbreaking PP
5D98 + PP 5D98 + PP 5D98 + PP 5D98 + 6,085 ppm 1835 ppm 1,000 ppm
1,642 ppm DEDPH DMDPH PP 5D98 Trig 101 DMDPB Units (270.degree. C.)
(270.degree. C.) PP 5D98 (270.degree. C.) (270.degree. C.)
(270.degree. C.) Average ppm* 0.339 ND ND ND 1.042 ND ten-butanol
ND = Not Detected *ppm level based on the weight of the second
propylene-based polymer sample.
As shown in Tables 3-5, the second propylene-based polymers
prepared from the inventive processes have excellent properties in
terms of melt flow rates, MWD (Mw/Mn) values, and reduced
by-products (for example, tert-butanol).
* * * * *